Figure 2.

5' end HoxA genes are repressed during cellular differentiation. (a) Cellular differentiation system used in this study. The human myelomonocytic cell
line THP1 was stimulated with PMA to cease proliferation and induce differentiation
into mature monocytes/macrophages. (b) Linear schematic representation of the human HoxA gene cluster on chromosome 7. Genes are represented by left facing arrows to indicate
direction of transcription. Cluster is presented in a 3' (HoxA1) to 5' (HoxA13) orientation. Same family members are labeled with identical color. Paralogue groups
(1-13) are identified above each gene. (c) Quantitative real-time PCR analysis of HoxA genes during cellular differentiation. Steady-state mRNA levels in undifferentiated
(left) and differentiated cells (right) were normalized relative to actin. CD14 and
ApoE expression levels were measured to verify cellular differentiation. Number below
each histogram bar identifies paralogue group. Asterisks indicate mRNA expression
below quantitative real-time PCR detection levels. Each histogram value is the average
of at least three PCRs and error bars represent the standard deviation.